The biodegradation of phenol and 2,4,6-trichlorophenol (2,4,6-TCP) by immobilized white-rot fungal cultures was studied in pinewood chip and foam glass bead-packed trickling reactors. The reactors were operated in sequencing batch format. Removal efficiency increased over time and elevated influent phenol and 2,4,6-TCP (800 and 85 mg l(-1)) concentrations were removed by greater than 98% in 24-30 h batch cycles. Comparable performance between the packing materials was shown. Increased lignin peroxidase (LiP) activity was detected with the introduction of the compounds and optimum activity corresponded to optimum removal periods. Higher LiP activity (16.7-19 Ul(-1)) was detected in glass bead-packed reactor compared to wood chip reactor (0.2-5 Ul(-1)). The presence of Mn(2+) in the wood material possibly effected elevated manganese peroxidase (MnP) activity (0.3-5.8 Ul(-1)) compared to low to negligible activity in the glass bead reactor. Reactor performances are discussed in relation to sequencing batch operation and nutrient requirements necessary to induce and sustain fungal enzyme activity in inert vs. organic material packed systems.